Cross recessed (+) flat head screw(Thread section50(Coarse Steel Unplated 3X55X50 Pitch 0.5

※For flat head screws, the total length includes the head.

The head has a flat top surface with a countersunk (conical) bearing face.
When specifying the nominal length, most other screws measure only the shank length; however, for flat head machine screws, the length is measured from the top of the head, so they may appear shorter than other screws with the same nominal length.

These screws are used when you do not want the head to protrude, or when you want the head to sit flush with the surface of the material being fastened.
However, a countersink must be pre-machined into the material to match the conical bearing face of the head. If this countersinking is insufficient, the head will protrude above the surface. Countersinking is also referred to as "sara-momi" (flat-head spotfacing) in Japanese.
Machine Screw Head Dimension Reference　How to Measure Flat Head Screws (Nejikuru Facebook)　Flat Head Screw Encyclopedia

Since hot-dip galvanized (dob) plating has a significantly greater coating thickness, it may not be compatible with other surface treatments.
In addition, even among hot-dip galvanized products, compatibility issues may arise when items are purchased from different suppliers.
Please be aware that returns may not be accepted in the cases described above, and proceed with your purchase accordingly.

• Cross recessed (+) flat head screw thread length 50 coarse pitch
• Nominal diameter (d) M3
• Length (ℓ) 55.0
• Thread length 50.0
• Pitch 0.5
• Cross recess number 2
• Head diameter (dk) Nominal 6 Tolerance 0,-0.5
• Head height (k) 1.75 Tolerance 0,-0.3
• Head chamfer (c) Approx. 0.25
• Cross recess (m) Reference 3.6